I guess, like everything else, it's a matter of personal preference? I know guys who are super into their partner being all sweaty and gym smelling. There's a reason there's money to be made in used schoolgirl panties. I also know guys who think that lady parts should smell like flowers and/or nothing at all. I saw on the internet that a lady from Real Housewives of Atlanta puts sugar in her pussy to make it taste good, which please do not do that, seriously.
I think it's generally understood that clean and healthy sex parts make for a fun time—no dick cheese, for example. But if you have the expectation that your partner is going to be freshly showered when you go down on them, that seems like something you should probably communicate to them before you get started. There's really no graceful way to say, mid-eat out, that's someone's pussy is unacceptably stinky. That's a "put your head down and power through" sort of situation.
Fundamentally, like you say, sex is kind of smelly. If you can't handle the fact that sex parts smell like sex parts, you know, fine, but realize that that is on you to communicate. Like, oh sorry, I have a thing, not ew gross, your stuff smells bad. On the other hand, everyone's got a different smell, and if someone has an infection or something, they could indeed have a very bad smell. Not saying that that was the case with you, reader, but just in general. I guess what I'm trying to say is that crotches are smelly, so if the particular crotch you are planning to put your face into doesn't smell the way you want it to, feel free to communicate that to the crotch's owner, but be gentle about it and don't wait until you're halfway there to bring it up.
How do I get the (very nice, natural) smell of my girlfriend off of my fingers and face after sex? I wash with soap but it seems to linger...
Mouthwash, scented soap, aftershave if that's your sort of thing. For all you hipster beardos out there, hair traps scent so soap those whiskers. I don't think this is science, but I find that touching iron or steel like you do to get garlic smell off works for some reason, though I also think some amount of the lingering is just the smell being in your nose/memory.